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Is it legal to own a F-18 Tailhook?
Sooo. Say I know someone who came into ownership of a decommissioned F18 Tailhook from an ex navy pilot that was left on a property during a land sale. I’ve seen similar ones in better condition for sale online for around $24,000. How would I find out if this is:

A Tailhook of an F18 (it looks just like the ones in videos),
Legal to own or still property of the US Navy?

Thank you for your question! It seems like you actually have three different questions here. The first one, how to identify whether it is indeed an F18 tailhook, is definitely on-topic here. The second one, whether or not it is legal to own, might fit on https://law.stackexchange.com , but if you go there, it's quite possible that you'll just be told to hire a lawyer (tbh that is a good idea). For the third question, an aviation forum might be a better choice; it doesn't really fit the Q&A format of Stack Exchange.

@MichaelHall I don't doubt your story, but I wouldn't attempt to export your tailhook as it's a controlled item on the US Munitions List (Title 22/Chapter 1/Subchapter M/Part 121). It lists under Category VIII-Aircraft and Related Articles, para (h) Parts, components, accessories, attachments, associated equipment and systems, as follows: subpara. (5) On-aircraft arresting gear (e.g., tail hooks and drag chutes) and specially designed parts and components therefor;

Hello MrsYowell, welcome to aviation.stackexchange.com. Try to make focussed questions to get focuessed answers.  If you want an answer to your first question, please include a photo of the thing. I removed the question about its value; the navy is not going to buy it from someone's garden, there are no privately owned F-18s as far as I know and thus the item will not be used on an aircraft again. The value is the scrap metal price or whatever someone is willing to pay for it.  This is not an auction site, so the question about the value does not fit here.

@MichaelHall No problem. I didn't provide an answer as I don't have a complete answer. Being on the USML, just means it would be illegal if you were a foreign national and did not have a license from the State Dept. Despite that, I've seen plenty of odd stuff at Property Disposal. It is plausible that it was obtained legally.

Captain Obvious here. You should ask the Navy. To be more precise, my first point of contact would be NAVAIR. They surely will advice you further if they do not have the answer readily available.
Possible way to ask about is that you/person X have come across the particular part on the premises you/person X have acquired, and you wish to know what to do with the part.
Please note that embargos related to sales of military materiel are not that uncommon. A close example is the sales ban of F-14 parts to any other party than museums. The fact that a part is decommissioned does not mean it is free to sell or possess by civilians.
For argument's sake, there is of course the option for this someone to FAFO, and just flip the tailhook on ebay for easy $10k. I personally would not have the balls for that.

Your best bet for determining which aircraft this came from is probably to look for a stamped number somewhere on the part and do a search by National Stock Number.
These parts do wear out after some number of arrested landings, and once the hook point fails inspection with a Go/No-Go gauge they are scrapped.  At sea they are likely to be pitched overboard, while ashore they would likely end up in a scrap bin somewhere.
Military bases used to have a local Defense Reutilization Marketing Office, (DRMO) where civilians could go to purchase surplus military items, but these sort of activities have been largely consolidated under the Defense Logistics Agency, (DLA).
Items with some purpose are evaluated, de-milled if required, and either dispositioned for auction or disposal. With such a specialized function, (and being on the munitions list as I point out below...) it is highly unlikely that tail hooks are ever offered to the public.  Any person in possession of one likely got it outside of approved channels.
While obtaining a tail hook outside of DLA would run afoul of normal administrative procedures, it is very unlikely that simply having one in your possession would be illegal, especially if it was acquired in the course of a legal property transaction vs getting caught dumpster diving on base.
If you were to sell it, however, it would be illegal to export under current Export Administration Regulations, (EAR).
Title 22, Chapter 1, Subchapter M, Part 121.1, of the United States Munitions List, under Category VIII—Aircraft and Related Articles, sub-section (h) states:

(1) Parts, components, accessories, and attachments specially designed for the following U.S.-origin aircraft: The B–1B, B–2, B–21, F–15SE, F/A–18 E/F, EA–18G, F–22, F–35, and future variants thereof; or the F–117 or U.S. Government technology demonstrators. Parts, components, accessories, and attachments of the F–15SE and F/A–18 E/F that are common to earlier models of these aircraft, unless listed in paragraph (h) of this category, are subject to the EAR.

It goes on to specify in more detail:

(5) On-aircraft arresting gear (e.g., tail hooks and drag chutes) and specially designed parts and components therefor

It is worth noting that the aircraft models listed are all in the current US DoD inventory, so it is very possible this restriction will be lifted once the aircraft are decommissioned.
P.S.  Regarding your since deleted bullet about value, I actually messaged the guy asking $24K to ask how he came up with this price since it's identical to one I have.  He laughed and said he didn't really want to get rid of it for sentimental reasons, but that he would take that for it.  So your comparison does not make for a fair estimate with something as niche as this.  And market value only has any meaning when there is a transaction to prove someone will pay some amount.

Excellent answer mr Hall! Regarding the price, for such a rare item, the correct price is usually stupid high. If the history of the said hook was traceable (and it should be), the documents attainable, and they showed actual combat duty, ask might aswell be twice as high.

I’ve never heard of any laws against owning an arrestor hook.  I don’t think possession of such a device violates export or ITAR laws - check with a lawyer who specializes in such things for further detail.  As to whether it remains the property of the United States government, you may check and see if the original owner possessed a bill of sale from the government for this item. It’s also possible that it was an expendable item or damaged during its use, and it was about to be discarded by the military when its previous owner picked it up and kept it. In which case, I don’t see how the US Government could claim ownership of device anymore.

Never having heard of any law regarding anything is hardly a valid point to guild upon. That being said, it is impossible to know the whole law, since as per the internet, the United States Code is made up of 54 titles, and each title contains multiple chapters and sections. In total, the Code contains over 52,000 sections, comprising more than 22 million words.

Which is why I put a note saying consult with an attorney if you are unsure.

Which, with all due respect, kinda voids this answer.

@Jpe61 In the U.S., everything's legal unless there's a law against it. The only difference between this answer and the same answer coming from a lawyer is that the lawyer presumably knows more laws, so "I haven't heard of such a law" would carry more weight coming from them.

Again: not knowing something is illegal is not an argument one should use in court if one happens to break a law...

@Jpe61 Agreed, but my point is it's not really possible to do better than this, except for the same answer to come from a seasoned attorney, or to find a recent case precedent where such ownership was argued before a court and ruled legal. How do you prove conclusively that something does not exist?

Surely the Navy knows about this... There always is someone who knows, you just need to ask the right person.

Just because something was going to be discarded does not mean it can be given away (or kept by an employee). Many companies have policies about this for old IT equipment, for example... to my understanding if they let someone have it instead of sending it to the trash, it could mess up their accounting. The US GOV isn't a private company, sure, but you get the idea.

No, but if they throw it in the been trying to discard it, there is no rule saying you cannot take it from there yourself.  I’m sure some pilot saw that his squadron’s maintenance shops were planning to discard the thing and decided it might make a cool thing to have in his man cave or some other thing. So he decided to take it.  It is a rather heavy object to try to take home!


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How does the relative wind on a propeller, strike the blade from behind (the non camber side)?

This may be a stupid or simple question, although any help is appreciated! :)
If possible, please answer without mathematical terminology. So I understand the concept of the blade increasing air momentum at the front, thus creating lower pressure, and I also get that the blade acts as an airfoil, lower pressure at the top, and higher at the bottom thus pulling it forward, and producing thrust.
My main issue is that I can't visualize how the relative wind physically travels behind the camber side, and hit the back side of the airfoil like in the diagram? Wouldn't it hit directly on the camber side if it's moving forward, not travel below, and strike it from the back? If someone can explain, that would be amazing!

Just Imagine the blade to be a rotating wing. This happens in wing also right; the relative wind velocity is below the chord and this is the AOA of the wing.
However, due to the high velocity of the rotation of the blades, the rotational velocity becomes significant over the froward velocity and therefore the relative wind hits behind.
But if the blades are in the feather position they are are approx straight to the forward wind and hence produce no thrust.

I assume you understand that that the propeller is twisted (the black bit of your picture). You might expect the blade to be flat like a ceiling fan, but instead it is angled towards the front (this angle does reduce at the propeller tips though).
The key is that the propeller is moving downwards - very fast. Consider when the aircraft is stationary - the relative airflow is coming from directly underneath. Because of the angle mentioned above, you can see that there is a high angle of attack.
When the aircraft is moving, there is also some airflow coming from the front. The combined effect is that the propeller thinks the airflow is coming at an angle, in your diagram labelled relative wind.

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Why is a turbofan engine less efficient when air leaks over fan blade tips?

Image source
I understand part of the reasoning for minimal clearance between the casing and the fan blades, is to have the larger fan blade possible, which generates a larger low pressure area to increase air intake.
However I don't understand why, if leaking occurred, it would reduce the overall efficiency.
If it was to leak, it's still going through the intake to the compressor or bypass duct.

"If it was to leak, it's still going through the intake to the compressor" this sentence is not clear and seems contradictory, unless you define "leak" (the fan wants air to go to the low pressure compressor, leak is supposed to mean air going from behind the fan back to the intake where it comes from). Perhaps you mean air entering the engine by bypassing the fan (this would not be called leak, and would be welcome, but this is likely not possible, as @Federico explained).

If it was to leak, it's still going through the intake to the compressor or bypass duct.

This is incorrect. A "leak" would cause the compressed air to circle around the fan and exit again from the front, reducing the efficiency of the fan, because part of the power would be used to compress air that does not do any useful work in the engine.
The circling around is a consequence of the work the fan itself does: after the fan the air is at a higher pressure than the air in front of the fan, this means that the air outside is pushed back by the air inside, and if there is a leak, the higher pressure air (inside) leaks out from the front.
Minimizing this "leak" helps maximising the efficiency of the fan, and of the engine as a consequence.

It would result in vortices forming at the blade tips, generating drag. Those vortices are the same that come off of the wingtips of airplanes and the blade tips of helicopters. Aircraft manufacturers have made winglets pretty much standard to minimize this drag, and not allowing the blade tips to give off those vortices (by putting them very close to the engine nacelle) will increase efficiency just like winglets do on a wing.

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How do blade cuffs help cool the engine?
How does the blade cuff (a fairing of suitable airfoil shape used to cover the shanks of propeller blades in order to reduce the aerodynamic losses) help cool the engine?

Source: An Illustrated Dictionary of Aviation

The cuff is used to change the pitch of the blades (or to create an airfoil when there is none) near the spinner. The cuff increases the airflow near the engine cooling intakes. The cuff is large, and larger at the blade root because the linear speed in this area is very small compared to the tip.
Lockheed P3 Orion

Cuffed blades of a Lockheed P3 Orion. Top: Photo by palmerphoto at RedBubble. Bottom: Photo by MDLPhotoz at Flickr
North American P-51 Mustang, cuffed vs uncuffed

Awesome photo by Allan Grant/LIFE Magazine, via This Day in Aviation
Captioned:

Joe De Bona and Jimmy Stewart with Thunderbird, their P-51C Mustang
  racer, April 1949. Placed on the ramp in front of the airplane is
  equipment that has been removed or replaced. Note the four “cuffed”
  Hamilton Standard propeller blades along the right side of the
  photograph. They have been replaced with un-cuffed and polished
  Hamilton Standard “paddle” blades.

More aviation photos by Allan Grant


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What is the fuel temperature in the tanks during a flight?
I'm trying to estimate the temperature of fuel stored in wing tanks during the flight. In my situation, I'm considering two wing tanks of 2000 liters each, one on each wing, at 20°C before the flight
I've run some calculations (I can provide additional numbers if necessary), and I end up with a temperature of 17°C after more than two hours of cruise (Mach 0.5, FL250)
Does this number sound correct to you? I was expecting a much lower temperature. I took a constant mass of fuel, which is not the reality, but even 15°C for instance seems rather hot. What are the usual temperatures of fuel in airliners tanks?

I'd be curious to see exactly how you got to 17.

I used a mutliphysics simulation software (amesim), to model the convective exchanges. I assumed a tank outside surface of 5m² on each side of the wing

This is related http://aviation.stackexchange.com/questions/2185/how-do-aircraft-keep-fuel-from-freezing-while-in-flight
"For example, at an actual temperature of -56.5 C (SAT) and Mach 0.72 the TAT is -34 C, but at Mach 0.80 the TAT is -29 C." so I guess something is wrong with your calculations.

Yes I saw that, thank you. It confirms that fuel stays above -40 °C at least. But it does not tell if it is more 10, 0 or -20°C. For my calculations, I took the r

For my calculations, I accounted for the ram effect: at 25'000 ft, the outside temperature is around -35°C, but at mach 0.5, the stagnation temperature is -22°C. Thus the cooling is not that strong

Well explained in this Mayday episode about BA38 disaster in 2008.

Quite cold, in fact.  External air temps at altitude reach -30 to -40 deg C.  The fuel in the tanks wil cool down and reach those temps within a couple of hours exposure.  Jet A has an icing inhibitor added to it to prevent freezing of the fuel in the tanks during extended periods in the stratosphere.
From a heat transfer standpoint, I would probably analyze this as a rectangular bar made from a composite sandwich of aluminum with a Jet-A center subject to convective cooling by air moving at a typical true airspeed, say 450KTAS at STP for FL250.  For simplicity we would ignore compressibility effects.  That may be where you erred.

Jet A1 may have icing inhibitor added but it's not part of Jet A1 by default. Many airplanes have heaters or other anti-icing systems and do not require it. If it is added it is at the point of sale at extra cost.

Temperature can even reach -74°C over Ural as noted in this AAIB report. That's an extreme,  but -54°C is common at the tropopause.

Yes but in the situation of regional flights (like with ATRs), you don't spend a lot of time in cruise (<2hours) and you don't climb that high. In this case I'm not sure you get below 0°C

@tintindu34: The lapse rate in the standard atmosphere in the troposphere is −6.5°C/km until reaching the tropopause (11 km). So 0°C is reached below 3 km AMSL (cruise altitude of an ATR-72 is about 5 or 6 km, so maybe -15°C, but well below -56C°, you're correct).


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What time do NOS IFR Charts expire?
My charts have 13 September 2018 on them.  What time do they expire?
I thought at Midnight that night local time, but have been unable to find any corroborating evidence.

In FAA-land the AIRAC cycle effective time is 0901Z. Your old charts were valid until 13 September 2018, 0900Z, the new ones are valid since 13 September 2018 0901Z.
I can't find the regulation that says it's always the case, but Google FAA 0901Z and you see that will give a ton of new charts / publications.
Here is a Jeppesen publication that explains the interpretation of the effective date.

Unofficial answer is 23:59z if anyone else has the same question.  Some FAA personal may or may not allow it till 12:59 Local.
The FAA inspector I spoke with could not provide me documentation on how he came up with that answer.
If you were slapped by the FAA for having expired plates on the day of, they probably were out to get you or your company and you may have a chance to get out of it since it's vague as to to when they really do expire.

Well, legally speaking, in a world where an FAA inspector is waiting to jump out from behind a tree to nail you for an infraction, it would be safe to say 23:59 Zulu on the 13th.  But in the practical world, end of the day on the 13th where you live should suffice.  In any case, I don't believe there is a regulation in the US that even requires a current chart for VFR flight.  So relax.

Thanks for the input, but it's for an IFR flight for a Part 135 Carrier, so it matters.

Are you concerned about getting dinged by your Capt or someone else in management doing a spot inspection of some kind?  It's still not like an FAA inspector's going to jump out from behind a bush with clock in hand.

FAA Inspectors.
I am the Captain. I ended up printing out new charts and plates from fltplan.com.
I fly into a major airport FAA inspectors are around all the time, some I know by name now that's how often they are around.
I had one come up to me today since he heard we were late getting our NOS plates and charts.
It would have had a problem if I didn't print them out this morning prior to my flight.
I also cannot use ForeFlight or similar unless it's been approved by the FAA and it is in my companies OpSpecs.

Holy crap. At least that was a next day thing.  I originally thought it was just a VFR thing you were asking about but in that case the 23:59Z on-the-date limit is your limit I'd say if it came down to getting busted or not.  I suppose you could ask an inspector if local midnight is ok, but I'll bet you'll get different answers with different inspectors.

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How to calculate "duty" when between flights in a 135 operation
Here is the scenario ... at 6:00am pilot flies from Location A to Location B to drop off a customer.  Flight duration is 2hrs.  Pilot is then given the day to do with as they want to but must be ready for the return flight at 22:00 later that day.  The return flight is another 2hrs.
Question: Has the pilot exceeded their daily duty limit under part 135 rules?  Or is it reasonable to assume the interval between flights would constitute a 10hr rest period?
NOTE: between the time of 8:00 and 22:00, the pilot was not paid and able to do anything they wanted with their time.  They were not expected to wait at the airport and knew they would not be needed before 22:00.

0800 + all postflight duties through the show time, approx 2130, would be rest if the pilot was really free of all company responsibilities.  I used 30mins as my pre and post-flight buffer and every inspector I dealt with believed it was reasonable.

@acpilot Please post that as an answer instead of a comment

I have not checked the latest regs, but the time beginning at the point where the pilot is done with all postflight duties until the time the preflight duties begin (ex. checking weather) is considered rest time ONLY IF the pilot is really off the clock.  If the company requires anything of the pilot (ex. "stay near the plane...just in case"), it is not rest time.


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What is the typical aircrew for a cargo flight?
What is the typical aircrew for a civilian (not military) cargo flight? From my limited web searches, it seems that there would be three crew members:

Pilot
Co-pilot (I assume there must always be minimum of two people in the flight deck, in case anything happens to the primary pilot)
Loadmaster, a crew member responsible for loading and unloading cargo, and for assuring load balance during the flight.

Are these indeed three minimal, required crew members for a cargo flight? Are there any others that are required or optional? What is typical for a long haul cargo flight, and what is typical for short haul. (Rather than precisely defining how many hours is long haul or short haul--I'm not even sure--I'll leave that open for the answerers, since I'm really not sure what to expect.)

Modern civil cargo flights can be divided into three categories: containerized-load, large-load, and feeder.
Containerized-load cargo (ULDs, standard pallet loads)
This is your typical UPS or FedEx flight; their flight crew complements are no different than a passenger aircraft flying the same route -- a captain and F/O for a short haul route such as one of the UPS A300s, and a captain, F/O, relief captain, and relief F/O ("heavy" crew) for a long-haul flight that needs them, although they may prefer to break such a flight up into segments, performing crew changes on the ground.  (Flight engineers aren't counted here since those aircraft are basically retired now.)
Bulk-load cargo
These loads (vehicles, large equipment, live animals, etc) require more attention, so loadmasters are more commonly seen on these flights.  However, the FAA does not consider a loadmaster "flight crew" in the sense that there are no licenses or ratings for the position; the training and qualifications for loadmasters are completely up to their employer.
Feeder aircraft
Feeder aircraft are often turboprop types (ATRs, for instance) that are too small to use standard-sized ULDs, so they are loaded in bulk on the main deck.  They use a captain and first officer pairing as well.
Either way, most cargo aircraft have room for supernumeraries (aka jump seaters), at least on the cockpit jumpseats if not in a forward or upper deck passenger cabin as well; long-haul aircraft will also have crew rest bunks fitted to that forward cabin area for use by "heavy" crews.

The context of this answer is 747-100 and -200 freighters at two airlines during the 1990s flying both civilian and military freight.
In the case of the 747-100 and -200 you had a 3-man cockpit crew: Captain, First Officer, and Flight Engineer. With the 3-man crew, there was no regulatory need to carry an additional pilot for a long flight. The 747-400 has, of course, a 2-man cockpit, but I don't know what the long-haul regulatory requirement was/is for an additional pilot.
There was no regulatory requirement to carry a loadmaster. If you were going between two stations that you regularly operated between, a loadmaster might not be carried if each station had trained loadmasters. However, if you were on a multi-leg, multi-day trip including stops where there wouldn't be loadmasters, one would be on-board (and maybe two if one of them was being trained). The loadmasters sometimes stayed with the airplane (or at least they used to) for periods of a few days to as much as two weeks even though the cockpit crews were changed out every day. Every few days the loadmasters would check into a close hotel for a quick shower or use a shower at an airport maintenance facility or some such. What always dismayed me was that they seemed to exist solely on catered food on the airplane for the entire time. While the airplane was in the air they slept when they weren't eating. Hopefully by now loadmasters are unionized and have better working conditions.
A mechanic was often carried if the airplane was having troubles or if it was being dispatched into Africa or other places where competent maintenance would not be available.
If you were carrying horses, there would be handlers with them. The one time I carried horses, they had a handler for each horse. Also, if you were carrying sensitive or very expensive cargo, there would often be someone to watch over it.
If it was a military cargo flight, there would sometimes be a 'military courier' or two aboard.
Jumpseaters were common, sometimes a lot of them depending on where you going, where you were coming from. The old 747s had 2 jumpseats in the cockpit and, typically, at least 8 first class seats on the upper deck, and often a bunk or two. I noticed in the accident report for the 747 freighter loss at Bagram that there were 7 persons aboard.

The main problem with jump seating cargo is ending up on that deserted island. :cD badum bump

A) You were the person I most expected to answer this (thanks for not disappointing!)  B) post-9/11 are cockpit jump seats available to paying customers?  C) A handler for each horse? That seems extreme!

@FreeMan Concerning the horses, these were race horses, at least the one time I carried horses. I was told the handlers actually stood at each horses head holding their halters during takeoff and landing. Concerning jumpseaters, that's what we actually called them, either that or ACMs (additional crew members) even though they were not sitting in the cockpit but back in the upper deck area. I don't know what post-9/11 rules are.

Post 9/11 cargo carriers still take jumpseaters. Generally the same requirements as passenger airlines and often very specific listing requirements. Ask your jump seat coordinator for details.

Great answer (I upvoted it), but I chose the other current response because it seems to reflect more current information. Thanks!


text:
Why are First/Business Class seats at the front of aircraft where it is the least safe?
According to this image, taken from The Science of Survivability (Page 79) from NOAA, the statistically safest seats to sit in are at the rear of the plane (69% survival rate vs 49% at the front).

From a business perspective (and ignoring any ethical considerations of whether passengers should pay more for a better chance of survival), it would seem to me to make more sense to put your highest paying and likely most regular passengers in the safest part of the plane, the rear.
Yet almost exclusively they are placed in the front, the un-safest part.
So why are First/Business class seats in the un-safer front of the craft and not the safer rear?

FO/FO, simple as that

@dkwarr87 The image you have referenced displays the intensity of the shock wave when initiated in the event of head-on collision. Not all crashes are like that. Chances of survival depend more if your time has come.

Your chances of being killed at all are so insignificant that the difference between 49% and 69% is statistically irrelevant.  If an individual wanted to make it relevant, then the only statistically rational choice is not to get on the plane at all since you then reduce your chance of being killed in a plane crash to zero.

@Simon "in a plane crash", yes. "BY a plane crash", no, alas. I won't mention specifics, but a number of commercial accidents have resulted in deaths of people on the ground - even in some cases from aircraft at cruise altitude.

That presentation presents that image without context.  See this article, which seems to be the original source. The probabilities shown are the probability of survival given that there were both survivors and fatalities. It excludes all instances where either everyone died or everyone survived.

@Jefromi: Which is reasonable, given that both in the event that everyone dies and in the event that everyone survives, all seats are equally bad or good for survival, respectively. The only time choosing the location of a seat in a way to improve one's relative chances of survival toward other seat locations is when only some of the people survive.

Imagine the conversation. Vip: "why is my business seat on the rear of the plane?", hostess: "because in the event of a plane crash you have an higher chance of surviving..."

@RussellMcMahon That really is splitting hairs.  The chance of being killed in a plane crash, if you are outside the plane, are vanishingly small.  Completely irrational to even consider it.

@O.R.Mapper It's reasonable, yes. But that doesn't mean everyone will infer it when they see the image without context - it's still important to explain what it means, that the numbers are just relative probabilities.

See also: http://aviation.stackexchange.com/questions/11658/where-is-the-safest-seat-in-the-plane

@Simon re "splitting hairs" -> I agree. As an engineer I was just commenting on the 'to zero' at the end of "...  the only statistically rational choice is not to get on the plane at all since you then reduce your chance of being killed in a plane crash to zero." 'ALmost ... ' or 'essentially ... ' would not have woken the pedant within :-). Just North of the English-Scottish border is the small town of Lockerbie. There is NO signage to guide those who seek to what they are looking for. Asking directions feels wrong (and probably is). Drive through the town and the road to the cemetry ....

.... is quietly signposted. Walk through the original cemetery to the memorial behind, feeling like the intruder that you risk being. Take photos (as I did) with the very strong awareness that gawking tourism is what they wish to avoid. Most of the people buried there were in the aircraft. 11 were unfortunate enough to live in the wrong place. A very extreme outlier, but not quite zero. Nit picking ? Sure. But worth being aware of. Ground casualties are in the news regularly in their ones and fews.

@EmanuelePaolini VIP: "Booyah! Suck it, plebs!"

Business class is typically booked by managers. They can be and are replaced more often and easily than others. Sorry, couldn't resist ;-)

Excellent answers from everyone, very informative and helpful, thank you. So to summarise: the passenger comfort and convenience benefits greatly outweigh the statistically insignificant increase in chance of survival of a statistically unlikely event :)

Is the stat true and verified?

Really if I am worried about dying in a plan crash I will take the back of the plane because it cuts my odds of dying in half?   No if I am worried about dying on a plane I don't get on it.  If I get on the plane I want convenience.  They board from the front because the front of the plane is the closest to the gate.   Even in coach same price tickets the front sells first.

Useful article http://www.telegraph.co.uk/travel/travelnews/9957319/Which-is-the-safest-seat-on-an-aircraft.html

@Simon To be fair, both probabilities are vanishingly small in most cases. For the major U.S. airlines, over the last 13 years, more people on the ground have been killed by airliner crashes than passengers. To be more precise, there has been 1 of the former and 0 of the latter.

Farhan did an excellent job explaining the answer from a creature comfort perspective, but let me explain why from the standpoint of safety and public perception of said safety.
Firstly, the difference between the front and the back isn't as stark as the red and green colors might imply.  As your graph shows, the survival rate in the front is 49%, and the rear is 69%, and while a 20% gap is significant, it's not like everyone in the front always dies and everyone in the rear always survives.
Secondly, planes simply do not crash all that much, and most frequent fliers just aren't worried about dying in a plane crash, so they'd rather the convenience of the front of the airplane.
Thirdly, of those who are worried about dying in a crash, most of them are unaware of the fact they are 20% more likely to do so at the front of the craft.  Most people assume that if the plane crashes, they are just going to die.  Thus, they assume moving to another part of the airplane isn't going to help.  Thus, there isn't really any market demand to move 1st class seats to another location.
As a final thought, I think even knowing the stats, personally, I'd still rather be up front.  I've read of accidents where there were several people near the rear who survived the initial impact and then either died from exposure or died from a spreading fire because they were too injured or weak to move.  Morbid as it is, sometimes I think I'd rather just "get it over with"...

Also note that the chance of death only applies if some, but not all, of the passengers die during the crash. Since many flights that crash crash with total fatalities, the difference is even lower than one would think.

@MarchHo absolutely; these numbers don't show the interesting bit, which is "chance of dying per flight at the front vs at the back", which are both absolutely tiny.

There are several reasons:

First In, First Out
They are given precedence to board the airplane before others, and precedence to disembark the airplane before others too.
Quieter Environment
On commercial airplanes, engines are on the wings which are in the aft of first class. Hence first class is quieter, which is a better experience.
Low Turbulence
Turbulence at the front of the plane is lower than the back. Aircraft are extremely flexible and will bounce around more in the back than the because the bump hits the front and causes the back to vibrate.
Seating Arrangement
Important and prominent passengers feel that they should be in the front or on the upper deck (747 or A380), when available. They also feel that they do not need to see other parts of the airplane which are not of their concern.
Marketing Strategy
When economy class people walk through first and/or business class, they will notice the perks and benefits of traveling in these higher classes. They may upgrade their seats on future travels for a higher price.

Excellent points. And all of these are much more important than the extremely small chance that the plane will crash and first class doesn't fare well.

Not sure about your turbulence point. I would expect the majority of the force of turbulence to catch the wings and tail (which are designed to catch the air) and therefore front of the plane get shaken more these remote forces.

It's that or the elastic property of the fuselage allows it to dampen turbulence from the wings before it reaches the front. Both might be true at different levels of turbulence.

I would agree to point 1 through 3 and 5, but aren't point 4 just a personal reflection? Is it proved to be evidence that first class and/or business passengers aren't interested in seeing the plane? Not that I see any reason for them to explore the plane - I just find it non-science. :)

@KristoferGisslén How many rich people would like to see the lifestyles of less richer or poor people? Specially, when there is no benefit of doing it.

I don't know. I only questioned the evidence behind that point of your answer as I do believe you've backed up the rest of your answer with quite solid evidence (or at least it seems credible) :)

I was under the impression turbulence is lowest around the wings, since the airplane pivots around the wings during turbulence due to its CG and point of support being near the wings. See http://www.askthepilot.com/questionanswers/turbulence/

I see how leaving first is good, but why is entering first desirable at all?

If you enter first, you get early access to the booze! You don't have to wait in a line on the jetbridge. You have first pick of an overhead bin to put your expensive suit in.

@gerrit you also get to put your carry-on in the most ideal location - i.e. close to you, without moving other stuff out of the way, etc. - if you board last, chances are you will end up with something under the seat in front of you

Entering first becomes desirable if the seat on the plane is significantly more comfortable than the seats in the waiting area.

On some foreign airlines, the boarding is not done from the front, but from a door that exists at the boundary between first class and eco class. The eco class people never see first class.

@Walter Not just foreign airlines; that's reasonably common whenever there's a door there, because it's more efficient (I've done it on a United 757).

@gerrit Depending on door placement, how much would a first class person enjoy passing through an area where a broodmother and her uncontrollable brood of 3-5 broodlings had been seated before first class could board?

@Farhan I've accepted Jay Carr's answer as it answers the question from the safety pov, but I really like your answer as well as it explains it from the airlines pov. It's a pity I can't accept both as the answer or I would :)

Looking at the diagram of fatalities, it's immediately obvious that the majority of people are in the safest spot. The most spaced out people are in the deadliest spot. This seems rational to me.

From a business perspective (and ignoring any ethical considerations
  of whether passengers should pay more for a better chance of
  survival), it would seem to me to make more sense to put your highest
  paying and likely most regular passengers in the safest part of the
  plane, the rear.

From a business perspective, it makes sense to keep your number of reported casualties as low as possible. Also from an ethical perspective, too, obviously.

I'm pretty sure this is not the actual reason, but I like the way you think.

Yeah. Likely just a psychological thing, where people feel like they are being treated as more important if they are in front.

FIFO (as Farhan mentioned) is the main reason. Most of the people up front tend to be business travelers who have to fly very frequently and want to get off the plane and out of the airport as quickly as possible. Additionally, getting off first makes them less likely to miss close connections. Getting on first means that they are ensured that overhead space will still be available and also allows them to relax and get something to drink while everyone else stands in a line waiting to board. The people up front tend to be more frequent fliers than particularly wealthy fliers, due to upgrades.

FIFO would be the definitive truth if everyone entered the plane through the tail, and exited through the nose. Obviously, they don't.
First class is ahead of the exit in most planes I've been on. If it were behind the exit, and everyone else ahead, nothing would change in terms of FIFO: first class would still be let out first, then everyone else.
In some planes, first class is even entered through an entirely separate door.
So, FIFO seems clearly not the main reason. Psychology seems the main part, continuing a tradition that goes all the way back to the captain's cabin in sailing ships.

Because, like in so much else, we trade off safety for convenience.
Why fly at all, if you want to be inconvenienced, but safer? Okay you couldn't get where you're going, but it's (almost) impossible to be involved a plane crash if you aren't on a plane.
The real answer is that statistically, very few people are ever involved in a plane crash. Of those, statistically very few die.
As stated in my answer here, if you got on a random plane right now, and then at every airport immediately disembarked and got onto another about to leave, it would take you something between 20 and 100 million flights before you died.
So you have a 0.00000001 to 0.00000005 chance of ever dying in a plane crash. That's so close to negligible that it isn't a factor. And if you survive a plane crash, are you really likely to be grateful to your airline for putting you in the nice "ever so slightly safer" seats in the back?
The statistics of the "safer" seats is based purely on accidents which have a proportion of fatalities: it excludes accidents where everyone or nobody dies, and ignores injuries.
In short, you're looking at a statistically insignificant statistic about which seat is "safest" on a plane that will almost certainly not crash anyway, and even if it did, everyone would be probably be fine (85% of accidents have no fatalities).
Compare that negligible difference in safety, with the 4.5 million passengers per day, of which approximately half a million (10%) or so are likely business class.... and you're looking at massively inconveniencing 182 million of your best paying, most impatient passengers every year, in exchange for making them ever-so-slightly less likely to die in an accident they probably wouldn't be involved in in the first place.
If I'm in a plane crash, I'm probably either dead or not... my concern is not whether I'm going to use my frequent flyer miles, nor where I'm sat.

If I'm in a plane crash, I'm probably either dead or not Probably? You are definitely either dead, or not dead. Sometimes life is very simple.

That was the joke ;-) although if you ask Schrodinger (or, for that matter, his cat), I'm both for a while until somebody checks.

@JonStory In this context I thin all observers carry their own cat.

@RussellMcMahon - that probably depends on the airline :)

As a high paying passenger what would you prefer, that you need to walk all the way from the front of the aircraft to your seat through a narrow walk way or be able to be seated immediately and not look at the lower class?
Rear entry is not used because the wing it in the way of the jetty.
Putting them in front also allows you to call them later so they don't have to wait in their seats as long before departure and lets them wander the gate and spend more in the shops.

call them later for a date? Seriously, though, don't most airlines board first class as "priority boarding", which means they're on the plane first? That part makes no sense.

@FreeMan Business class seats are more comfortable than airport benches, and it gives business class passengers 1st claim to economy overhead bins if the business class ones get full...

In both jets and propeller planes, the section of the plane in front of the engines is generally the quietest. The ride tends to be smoother as you get further away (in either direction) from the wing, too. The common answer that the seats are up there to speed loading and unloading might have been true back in the day, although most airliners still board through a forward door (either the first or second door on the left is most common).
I suspect the real answer has to do with legacy airliners, though: back in the day, first-class seating was in the front, and now it's there because that's where it's always been.

"The ride tends to be smoother as you get further away (in either direction) from the wing, too": Is there evidence to support that?  I had always heard that the ride is smoother close to the wing, and anecdotally my experience has been that the back of the plane (which is far from the wing) has the roughest ride.

All these answers seem to disregard the obvious cultural aspect: being up front is seen as more prestigious, and was so long before airplanes came along.  First class cars in trains tend to be in front, the more expensive seats at a play or sports event are up front, at formal dinners the higher-status guests are seated closer to the head of the table, in the days of segregation black people had to ride in the back of the bus...

More (likely) ways to Die
I'm going to add another twist: There are more ways to die in a plane than in a plane crash, which your question implies. Business class is spacious, comfortable and relaxing. Economy class is loud, tight and uncomfortable.

If your movement is restricted, you could get Deep Vain Thrombosis. More a risk in economy than spacious business class where you have the space and comfort to move.
You are sitting closer to a load of other passengers who could in theory give you some flu or something in economy than business.
You are treated like livestock in economy and correspondingly more stressfully. It wouldn't surprise me if you're more likely to get a heart attack for that reason than you ever are to die in a plane crash.

In my humble opinion: If you're sufficiently concern to be reading this, book a seat in business: relax in the lounge before the flight, sit with fewer passengers, have the flight attendants close at hand if you have questions or concerns and enjoy some good food.

Dataset Limiations
Your data is limited in that it does not go into the change of risk depending on the conditions in which you are flying. If you're flying over water, there is the ever-so-marginal risk the plane might ditch. You are then better off in the front, since it normally doesn't strike the water and floats nose-up. There are unpleasant stories from US1549 (Hudson Crash) about the rear of the plane, whereas the evacuation at front was relatively clam. Depending on the specific destination, you might be better off in another section of the plane. This is the reason why there is no clear trend and just about every authority including Boeing and the FAA says that every seat is as good as any other seat.
Furthermore, your data is based upon accidents dating all the way back from 1971. This is not really a representation of the current risk since the causes of accidents have changed. For instance, Ground Proximity Warning Systems (to stop you flying into mountains) was made mandatory for Part 121 and Part 135 operators only in 1978. Incidentally, the types of accidents this applies to involves going into terrain nose-first.
Bottom line is that probability is so incredibly remote it is virtually impossible to put halfway reliable number to stuff like this. Unlike vehicle traffic, the fatality rate jumps substantially depending on how many accidents just happen to occur that year.

Regarding the first part of this answer, it doesn't really answer the question. All of those points about the reduced risk in business or first class would still be true if it were at the back of the plane, as they have to do with seating arrangement, not location within the plane. Regarding the second part of the answer, crashing short of a runway on land would normally be more deadly in the back, too, since planes flare nose-up to land. For example, all of the deaths and the vast majority of injuries in the Asiana SFO crash were in the back.


text:
Where to do the Run-up and Safety on the Return Flight?
At my home airport, we do the run-up on the ramp, but I guess each airport has its own preference.
What is the "standard" run-up location? If I recall from my training early on, you can do it at the runway if you angle yourself against the departure end. If this is correct, how do I know that I've angled myself in a way not to blow any debris into an aircraft behind me. And if I do the run-up at the end of the runway, don't I risk obstructing an aircraft that wants to takeoff behind me but has to wait for me to do the runup?

I removed your second question (about preflight checks after a short stop) because it's largely unrelated to the question about where to do a run-up. Stack Exchange works best with one question, or a couple of very closely related ones, per post. It's a perfectly good question, though -- you should ask it as a separate question. If you click the "edited [some time] ago" link below the question, you can see the revision history and copy-paste the text to a new quesiton.

Hi David. That was very gracious of you! Thanks.

I would do the run-up at the following locations (in order of precedence):  (1) Where specified by the individual airport's local governing authority, (2) at the taxiway which you will use to move onto the active runway or (3) on the runway at the point you are going to begin your take-off roll.  If using #2 it is good to turn your aircraft so that it is facing into the wind, which will usually result in your prop-wash NOT affecting an aircraft which may be directly behind you in the take-off queue (it will normally be off to one side at that point). And #3? Go back to #2.Don't block the rwy!

The simplest thing is to ask someone local where runups are usually done: the FBO, Ground Control or another pilot. If you can't find out then you can do them anywhere you like as long as it's safe.
Some airports have specific runup areas but they aren't always obvious. For example, KPDK has runup areas at both ends of taxiway A, they're shown on the airport diagram as 'bulges' in the taxiway but they aren't labelled. You might notice them when you land and taxi but you might not. I've circled one of the runup areas in red here:

If there are no runup areas, the 'default' location is the one you remember from training: on the taxiway just before reaching the runway, angled into the wind. If the taxiway is wide enough, you can move to the edge so that other aircraft can pass you if they're ready before you. That's very common and it's what many pilots will expect you to do, even if you have to block the taxiway for a couple of minutes. This is where you have to use some judgement: if you know that you need to take your time on runups - perhaps it's an unfamiliar aircraft, or you've just had maintenance done and you're double-checking everything - then you might look for another spot where you won't be in the way.
Blocking other aircraft from reaching the runway is always a possibility, but at airports with a lot of GA traffic - and especially a lot of flight training - it's common and just something to be expected. That doesn't mean you should take forever doing your checks and of course some other pilots will always get annoyed at even minor delays, but if the only safe place to do runups is the taxiway then just do them there and the others will wait.
Another option is to do runups on the ramp or before entering the movement area so that you don't block other aircraft anywhere. That's especially important at airports with scheduled commercial flights because they usually have very precise departure times and getting stuck behind another aircraft for even a few minutes could be an issue. If you're in that environment, then you should definitely check with Ground Control what they want you to do. But be careful about doing runups on the ramp because of people and vehicles moving around. Also be wary about doing runups a long way from the runway: during a long taxi you might change something (e.g. the mixture or fuel controls) and then forget to reset it for takeoff.
The one place you should never do runups is on the runway itself. Sitting there for several minutes blocking the runway for landing traffic and unable to see final approach behind you isn't a good position to put yourself in.
Finally, avoiding blowing debris into other aircraft should be simple: just look around you, and don't position the aircraft so that your prop blast is going somewhere it shouldn't.

First link 404s at me

@StarWeaver Thanks, I've edited it. A lot of FAA links aren't very stable.

Old Q, and very good answer, I'd like to emphasize a couple of things. Place: always at hold short point before takeoff or at seond in line unles specifically ordered otherwise. Never take off with an engine that's been idling for minutes. Alignment: turn slightly so that plane behind you does not get blasted. How do you know if there is someone behind you? Well, as PIC you are supposed to know what's going on around you, so eyes and ears open all the time. Just as much it is the responsibility of the PIC behind you to maintain adequate distance, so excessive(30+deg) angle is not necessary.

The shortest, simplest (but probably least helpful) answer is that it depends on the airport.
At DFW there's a fairly large holding area on each side of the 17L-35R GA runway, with space to turn before reaching the hold short line. Departing aircraft can do a quick runup at the line while waiting for clearance to enter, provided the following aircraft has some idea of what's about to happen and isn't tailgating. If the pilot misses this opportunity because a following aircraft got too close, he can still do a full runup on the numbers prior to releasing wheel brakes.

At the smaller Addison Airport, there's only one main taxiway that's fairly narrow and close in, so they built a special "cul-de-sac" specifically for runup tests.

The usual procedure is to taxi to face south to do your runup just shy of the stop line, pretty much where the plane in this image is. They might have originally intended small planes to face west, but that's dangerous for jets to try as there's road traffic fairly close in just the other side of a fence, so now they just say face south whether you're in an LSA or a 737. Other aircraft are supposed to hold short of the stop line to the right, but if you have several small craft in sequence it's fairly safe to have a second or even a third aircraft in here. If someone gets too close behind you in here - lots of student pilots fly out of here so you have to be ready for anything - you can do your runup on the displaced threshold. Of course you can only enter this area with takeoff clearance (or at least a taxi and hold), so if you find a problem here it's slightly more inconvenient, but you can still quickly duck out of the sequence using the runway exit in the picture.


text:
Is there a "Quid Pro Quo" of flight following?
I like to use flight following whenever possible because who wouldn't want traffic pointed out to them for free?
But just as the controllers are doing me a favor, they sometimes ask me to do them a favor.
For example, depending on a given runway configuration, they might vector me way far out from the airspace. During times like these I end up just wanting to terminate. I'm far clear of the class C, and they've added 20 minutes to my flight.
How is it that they move me so far away when plenty of aircraft who didn't even bother to call up approach are flying so freely without incident? To anticipate objection, this is while staying out of the charlie itself.
Is there anything I can do to ask if I can change altitude to avoid rerouting? I'd hate to call up, have them assign me a squawk, and then say "like to terminate" moments later.

While on flight following, you ARE under air traffic control (just on a VFR flight plan). It may be different elsewhere, but in the United States, pilots are required to follow ATC instructions while in controlled airspace, per 14 CFR 91.123(b): "Except in an emergency, no person may operate an aircraft contrary to an ATC instruction in an area in which air traffic control is exercised." The pilot would need to terminate FF in order to avoid having to follow ATC instructions.

@newmanth A VFR flight plan and FF are totally unrelated; ATC doesn't even know if you have a VFR flight plan. And of course you have to follow ATC instructions, but that assumes you're under radar control. It isn't really clear (to me) from the question if the aircraft was under radar control at any point or not, hence my question about phrasing.

@Pondlife, you are correct about the flight plan part.  I should have instead said "VFR flight".  Whether or not the flight is under radar control is not relevant, as ATC will deny flight following if there is no service and will terminate if they lose radar contact.  My only point was that as long as a pilot is in contact with ATC they are obligated to follow controller instructions, regardless of the type of flight. I only posted this to make sure someone doesn't come by this question, and start thinking ATC instructions were optional during VFR flight.

Wait, ATC doesn't know about VFR flight plans? It's not in their system just FSS?

The controllers are not "doing you a favor", they are doing their job!

There is indeed a Quid Pro Quo with flight following: you're adding to the controller's workload, and they may ask you to do things to help alleviate that workload (like not flying through a busy approach/departure corridor).
Some controllers will also vector you around a hot MOA (even though you can fly through it VFR their normal operating mode is for IFR traffic) while others will simply alert you that the MOA is hot and leave it up to you to decide how to handle that.
Because there's no language in the ATC manual for "Hey could you please fly around this area so you don't make my job harder?" when controllers want to ask you to do something they use the language they do have, which takes the form of instructions (vectors).
As a pilot you should remember that vectors are the opening round in a negotiation: If a controller gives you a vector you don't like you can always ask them why, and often you can negotiate for something better.
This is true for IFR flights as well - The only exception is when a controller uses the word "Immediate" or any variation thereof (then you do what they say and ask your questions later).

If you know you'll be flying through an arrival or departure path you can offer to change your altitude to stay out of the way. Your handy VFR Sectional or Terminal Area Chart shows some of the arrival and departure paths for busier airports:

If you offer a climb or descent controllers will usually tell you what altitude they need you at so you aren't in the way, and if they're not forthcoming you can ask ("What am I being vectored around? Can I go through at a different altitude?").
Finally remember that as a VFR flight you are under no obligation to accept their vectors in Class E airspace: If you don't like what the controller is asking you to do and can't negotiate something better simply say We'd like to cancel flight following at this time and continue on your own navigation (keep listening to the frequency to see what they do and maybe you'll come up with better alternatives for your next flight).
The controllers may grumble about it, particularly if they just put you into the system and you immediately cancel services, but that isn't your problem.

I'm no expert but I think the official phraseology is "cancel flight following" or "cancel advisories". Whatever "you'd like to" do at any given time really isn't interesting to the ATC (and in situations like these, probably somewhat unprofessional).

@KeithS You'll hear both but you are right about "cancel" vs. "terminate" (fixed). What the pilot would like to do is always relevant though: We're the ones flying. (It also sounds better/nicer than N12345, cancel flight following. - while I'm all about concise transmissions it does help to remember you're talking to a human being on the other end of the radio.)

Yes, if you are receiving radar services you must comply with ATC instructions. And contrary to voretaq's otherwise excellent answer, simply electing to terminate radar services so as to avoid those instructions or restrictions is not necessarily an option.
There are two reasons for this, one legal and one practical.
Legal answer
Let's look at 14 CFR 91.123 Compliance with ATC clearances and instructions. Paragraph (a) concerns ATC clearances. When you're on flight following you don't receive clearances except for practice approaches or Class B operations, so that doesn't really apply. But look at paragraph (b):

Except in an emergency, no person may operate an aircraft contrary to an ATC instruction in an area in which air traffic control is exercised.

That's pretty cut and dried. There are only two exceptions: 1) if an emergency exists or 2) if you're not in an area "in which air traffic control is exercised," i.e. uncontrolled (Class G) airspace. If you choose to call ATC and request radar services, and ATC issues an instruction, you must comply with that instruction. You can request to terminate radar services and change your frequency, but the controller is well within their rights to disallow termination. Note that when terminating radar services ATC will use the phraseology "frequency change approved" or "change to advisory frequency approved." This approval is not guaranteed!
(To counter the claim that "an area where air traffic control is exercised" means only Class B/C/D airspace, compare the wording in the AIM 4–3–2a vs 5–4–3a.)
Practical answer
Consider the reason you called ATC in the first place.
It might be that you wanted to transition certain airspace and being in two-way communication with ATC is a requirement to enter that airspace (B/C/D). In that case you will have to remain in contact with ATC and comply with any instructions they give in order to remain in the airspace.
But it might be that your route remains entirely within Class E airspace; communicating with ATC is not a requirement, but you decided to do so anyway. Why? To receive traffic information! You still have a legal responsibility to see and avoid other traffic, but because you are receiving radar services ATC will call traffic that may be a factor and thereby help you carry out this responsibility. If ATC issues an instruction or restriction, it is to keep you away from traffic you might be unable to see or avoid—we do not issue vectors for controller amusement.1 Any instruction you receive will be because the controller thinks it is necessary to ensure the safety of your flight. Why would you choose to discontinue this service exactly when it would be most helpful to you?
Certainly, as voretaq points out, you can query an instruction and suggest (or ask for) an alternative. But if the controller is unable to issue an alternative instruction, you must comply.

1Vectors for controller incompetence are another matter.


text:
Which cruise altitude is prefered in engine-out operations of Boeing airplanes?
On Engine Out Operation in Boeing Airplanes, which altitude is preferable, the OPT Altitude, the MAX Altitude or the RECOM Altitude of the ENG OUT CRZ Page?

You'd typically drift down to your max single-engine altitude, which means essentially that max continuous power on the operating engine is sufficient for level flight at that altitude.  Higher than that, you have a slow descent going in order for the thrust you have to maintain the recommended driftdown airspeed.
In general, there wouldn't be any advantage to descending lower than this until you need to do so for approach and landing, so you'd probably remain at that max altitude.  As you burn off fuel, your max engine-out altitude would slowly increase so (hypothetically) you could actually step-climb up a little bit if you were going to be at that new Single Engine cruise altitude long enough, but in practice you'd need to lose the engine a LONG way from landing before the idea of step-climbing up to a higher SE cruise altitude would make practical sense.
The "Max" altitude is only reachable with the thrust of 2 engines, and the "OPT" altitude is probably well above what your max SE altitude is anyway -- it's optimum for cruising with both engines operating, after all.  Granted, a sufficiently high Cost Index and/or strange winds can pull the Optimum altitude down, but in 99% of the cases, Optimum is going to be well above Max Single Engine altitude.

max single-engine altitude - in a 747? ;)

Yeah, it's not un-heard-of for a 747 in an ultra-long-haul op to step or cruise climb on 3 engines.

@UnrecognizedFallingObject My (jokey) point was that Ralphs answer only addresses twins.  It ignores the 747 when the OP asks for "Boeing".

What about a B-47? Or B-52?

The preferable altitude is the one you ve been recleared  to! Especially on airways over congested airspace. Also you have to consider wind and temperature if you are going to a looong ETOPS before deciding to go for MAX or RECMD.

@Houba  In the case of having lost an engine, you will have declared an emergency so you'll probably be cleared for whatever altitude or block of altitude you need.  You may well also turn out of the tracks so that you can petform the gradual driftdown descent clear of traffic.  But "not descending" is hardly an option regardless of ATC when that motor quits.  You're correct that temp & winds are used in the FMC calculations that give you ECON + driftdown speeds & the various altitudes.

@Simon -- aye ;)

@egid -- BUFFs need new engines anyway :P

@RalphJ Thanks for the answer... I didn't wrote my question properly, because, when I wrote about the OPT, MAX and RECMD, I was assuming that it referred to the OPT, MAX and RECMD single Engine Altitude that the FMC displays when pressing the ENG OUT key, so the info shown in that case will be based on single engine operation, according to the FCOM Volume 2. Sorry for that...
Anyway, if the FMC give us an OPT engine out altitude, and a RECMD engine out altitude, shouldn't be preferable to use them, at least over the ETP of  an ETOPS 180 scenario, for example?

That's different FMC software than I'm used to, then.  Having Optimum + Recommended + Max altitudes all on the SE Cruise page is a new one for me.  Most curious how an "optimum" altitude differs from a "recommended" altitude.

@RalphJ The difference between the OPT and the RECMD Altitude for Single Engine and All Engine is predicted wind. I worked with some airplanes with the Honeywell Pegasus FMC, and you can uplink or entered wind prediction for each waypoint, on the Active Flight Plan, with 4 different altitudes for each waypoint. WIth that information the FMC calculates the recommended Altitude based on wind.

@aiglesiasn  Thanks, that makes good sense.  I'm used to a Smiths FMC rather than Honeywell, so different functionality there.


text:
What safety systems are currently being developed for crash situations?
I know commercial airplanes are gradually becoming safer thanks to the development of systems that are able to avoid the conditions that would lead to a fatality. But is anybody developing systems for minimizing deaths if a plane crashes? For example, cars have airbags and airfighters can eject the pilot's seat in critical situations.
It's a little bit disappointing to see that an aircraft's cabin still breaks into pieces when it crashes during takeoff or landing, causing deaths or injuries. Isn't there any way to make the cabin structure more break resistant at landing/takeoff speeds? Wouldn't airbags prevent people hitting their heads against the cabin's walls?
And now the probably naivest question: couldn't giant parachutes be installed on airplanes to prevent them from falling in case of stall or engines failure?

The question of why full-aircraft parachutes are not used have been discussed thoroughly in Why don't big commercial planes have full aircraft parachutes?

There is also Airbags in aircraft - is that just a military thing? to address your question about airbags.

The question of break resistance is most likely answerable by looking at the additional weight imposed by the stronger materials that would be needed to construct such an airframe, and what that would do to other aspects (payload capacity, fuel consumption, etc.) of the airframe design.

This question has a lot of information on the fundamental, physics-based difficulties of crash protection


text:
What is the most simple plane lift equation that gives realistic solutions?
I need the most simple lift equation that once solved with Mathcad gives a realistic vertical speed of a plane and implicitly the altitude h(t).
Also the drag eq. (1) leads to a good solution, a Vh(t) that increases and finally reaches a limit (the maximum horizontal speed) and stays there during the duration of the flight, the lift eq. (2) stabilizes at a Lift(t) - m * g = ct. > 0 and in consequence Vh(t) keeps growing indefinitely because an eq. of the type m * dVv(t)/dt = ct. leads to a solution Vv(t) that rises linearly with time.
Question:
It is quite clear that the vertical speed of a plane, Vh(t), can not grow indefinitely. How can I stabilize it to o constant value. What do I have to add in the lift eq.?
Drag eq.: m * dVh(t)/dt = T - Drag(t) (1),
Drag(t) = 0.5 * Cd * r * S * ( Vh(t) + Vw(t) )^2,
Lift eq.: m * dVv(t)/dt = Lift(t) - m * g (2),
Lift(t) = 0.5 * Cl * r * S * ( Vh(t) + Vw(t) )^2,
where:

Vh(t) = horizontal speed, Vv(t) = vertical speed, both of them have to be determined being unknown functions.
known parameters: m = the mass of the plane, r =  air density, S = the wing surface, T = thrust = ct., Cd, Cl are the drag and lift coefficients, g = 9.81 m/s^2, Vw(t) = the wind speed, that is usually a known constant but can have other forms given as functions of time, t.

Sounds like homework.

First, you need to add the effect of density $\rho$: Air density changes with altitude, and this affects both lift and drag (at least if you model airbreathing engines).
For lift $L$, use $$L = c_L\cdot\rho\cdot\frac{v_h^2+v_v^2}{2}\cdot S$$
For drag $D$, you should only simplify the equation as much as possible. Your equation is simpler still and doesn't model the increase in drag with more lift. The simplest practical equation will look like this: $$D = \left(c_{D0} + \frac{c_L^2}{\pi\cdot AR\cdot\epsilon}\right)\cdot\rho\cdot\frac{v_h^2+v_v^2}{2}\cdot S$$
More lift will need more thrust and will limit the upward acceleration. Climbing higher will reduce thrust in proportion with density and limit the possible speed range.
Nomenclature:
    $c_L \:\:\:$ lift coefficient (normally between 0 and 1.5)
    $\pi \:\:\:\:\:$  3.14159$\dots$
    $AR \:\:$  aspect ratio of the wing (ratio of span to mean chord)
    $\epsilon \:\:\:\:\:$  the wing's Oswald factor (use 0.8 when in doubt)
    $c_{D0} \:$  zero-lift drag coefficient (use 0.02 when in doubt)

I have changed the equations using the formulas for lift and drag given by you. This time I obtain an exponential growth for the vertical speed Vv(t), which is also an incorrect solution.

@RobertWerner How do you model thrust? Do you adjust it at all, or can it grow infinitely? How does a change in density affect it?

Peter Kämpf, the thrust and air density are constants in my case. Even if I change them like T = T(r, vh) and r=r(h) they do not influence too much the results unless they have really big variations. Finally I added a vertical drag term in the lift eq. which now looks like this:  m * dVv(t)/dt = Lift(t) - m * g - 0.5 * 2000 * Cd * r * S * Vv(t)^2 where this strange 2000 * Cd is the drag coefficient if one wants to lift the plane vertically. I get now realistic vertical speeds like 2 m/s but the lift eq. seems quite artificial. I am looking for a more credible lift eq..


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Is the certification process for unbraked wheels and tyres different from braked ones?
Engineering a landing system for a thing flying with helium. Do unbraked wheels and tyres have a different certification process compared to braked wheels?

If you're talking about aircraft certification, isn't it kind of necessary for us to know what jurisdiction your aircraft falls under?


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How to log FTD time during airline selections?
I'm currently going through some airline selections in Europe for which it is common to fly 45 mins PF and 45 mins as PM during the assessment. I'm wondering how I am, if at all, supposed to log this time. Only PF or both? I'm well aware that this time does not count towards my total time or flight time or instrument time.

In general, you can write whatever you want in your logbook; if you want to record being a passenger on a 777 from London to New York, go ahead.  What's important is that you only claim what's allowed to be claimed for a particular purpose.  So if you are applying for a license that requires XXX hours of PIC, then that 777 flight shouldn't be included in that total.
In order to keep logbooks "clean" and free of entries that will generally be ignored, pilots generally wouldn't log passenger time in the same book that they record actual flight time. (Yes, the 777 passenger example is an exaggeration, to make a point.) Unless you foresee a circumstance when time in an FTD, not associated with any training syllabus, would count toward something, the most common practice would probably be to omit it entirely from your logbook.  (If you were in a training program that requires a given amount of time in an FTD, that's a separate case, since then the FTD time would count toward meeting that program requirement.)
Alternatively, you could enter the event in your logbook, but with 0:00 in all columns, and your actual duration as a remark.  That way you'd have a reference that you spent X:XX in the FTD on that date, but nothing gets added to any of your flight times that could be questioned or, worse, mistakenly added, later.
The consequences of having been found to be inflating your flying times, even innocently, can be unpleasant, so the best practice would be to keep separate the times that count (PIC, SIC, student, XC, actual IMC, etc) from those that don't count and are only of interest to you.


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Yellow chevron markings at end of runway, what do they mean?
In this YouTube video (link starts video at time of interest), the pilot appears to land in the area marked by the large yellow chevrons, in what appears to me (a layperson) to be a taxi way.

What are the meaning of the yellow markings? Under what conditions can a landing be made before this point?

Those are not chevrons but arrowheads used to mark the start of the runway. So, yes, he did land on the taxiway.

Source: FAA Airfield Standards Quick Reference
He does land slightly before the runway threshold. He even says he is going to land short. Since there was nothing on the taxiway leading to the runway then it seems there is no problem doing that.

screenshot from Google maps of KYKM runway 22 threshold
For comparison, chevrons mark either stopways or blast pads and look like this:

same source as first image
They may include an EMAS bed, so touching down there would not be a good idea.

Are there markings meaning "absolutely no landing here" for some extension at the end of a runway?

I would say that it's not a good idea to land on chevrons, which are a little different from the arrowheads. Chevrons can be on an EMAS bed. You don't want to touch down there as it can damage the EMAS and likely the plane. Chevrons look like this

This is a good answer, the pilot in the video showed poor judgment landing there, and then posting it for the whole world to see.

@BaileyS It can mean that. Displaced thresholds can be used for numerous reasons. Sometimes it is for a blast pad, which is not intended for landing. Sometimes it's there to allow a stopway for the opposite runway which may or may not include an EMAS bed. It can be temporary, for construction. There are regulations as to the heights and distances of obstacles from the end of the runway. If you look at this question it appears the runway was a bit too close to the road. It doesn't necessarily mean it won't hold the weight.

Edited the answer a little. After reading Donna Speidel's answer I watched the video again and the arrowheads are clearly yellow. They looked white in the satellite photo. So it's not a displaced threshold, but markings to indicate where the taxiway ends and the runway begins.

Yellow arrowheads before the threshold bar mean you shouldn't land or take off in that area.  White arrowheads mean you can roll out from that area, just not land.  The displaced threshold is usually there due to obstructions or construction.


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Who pilots an aircraft that is on a delivery flight?
Right about now (Jan 28, 2016, 08:12 UTC), a Boeing 737-8AS is cruising over Manitoba/Nunavut on a delivery flight from Seattle Boeing Field (BFI) to Dublin Airport (DUB). The flight is labelled RYR800F, and is clearly a delivery flight for the European low-cost airline Ryanair.

I have always wondered who flies the plane in such situations. I would appreciate if you could give me a few insights into how these events are managed by the manufacturer and the Company. I envision the following cases, but which one of them, or combination of them, is true?
1) The plane is flown by a special pilot unit of the buying Company, which flies to the manufacturer's logistic airport, checks for conformity, signs a few documents, and then flies the plane to the Company's headquarters or hub;
2) The plane is flown by a special pilot unit of the manufacturer. They fly the plane to the Company's headquarters or hub, then meet the buyer to check for conformity and sign the documents. Eventually, the pilot unit flies back to manufacturer's base as regular passengers onboard other flights;
3) The plane is flown by two units: one belongs to the manufacturer and the other to the buyer. They check for conformity, sign the documents, and jointly fly the plane, in order for the manufacturer and the buyer to share immediate feedback on the plane's performance while airborne;
4) The plane is flown by a contracted pilot unit, which performs the duty as a third party payed by the buyer or by both the buyer and the manufacturer. This unit also includes a member of the buyer. They reach the manufacturer's base, the buyer's employee signs the documents, and then the plane is flown to the Company's headquarters or hub.
I assume each Company has its own policy in this regard, but which one of these procedures do you think is the most common? Thanks!

Well, mine is intended to be a general question regarding commercial avaiation, even though it is based on a specific case involving a Boeing 737-800 and Ryanair. Therefore, Embraer, Canadair, and others are not out of scope.

Related: Who flies planes on ferry flights?

Not related, not really. I posted that very question, and it was mainly about ferry flights for aircraft that are bound for logistic airports in the likes of Victorville. This question is intended to address the issue of delivery flights only.

your first question (in the link provided by mins) reads When an aircraft has to be delivered, who flies it to the destination airport? how was that mainly about ferry flights for aircraft that are bound for logistic airports?

This website is becoming full of excessively picky people. You are worse than a peer-reviewed journal. Get over yourself, little justices.

As part of the handover there is an acceptance flight to demonstrate that everything is in working order. There are staff from both buyer and seller on board for this. My guess is that the acceptance flight happens at Boeing HQ (where they can easily fix any issues that come up) and the buyer is responsible for flying the plane after the acceptance flight. Ergo, pilots from the buyer would be flying it. But that's just my uneducated guess. The fact that the flight has a Ryanair label also indicates that the buyer is probably flying it.

Ryanair captain told me that Raynair pilots deliver planes. But he himself was not very interesting in this kind of mission :)

Typically the customer will travel to the manufacturers location for a final inspection and acceptance of the new aircraft. This includes one or several test flights with staff of both the manufacturer and the customer on board, thorough systems checking and final modifications if necessary. The acceptance of the aircraft is then made official by signing off a pack of papers.
Then the customer transfers the final sum of money to the manufacturer and the aircraft is signed over to the customer. The delivery flight is typically operated solely by the customer's staff, however if it is the first aircraft of the specific type for the customer, the manufacturer may send training staff along for final training of the ground staff at the customers location if agreed so.

as it happens,a very good friend of mine,is a captain with Ryanair(based at Stansted ) he is one of the senior pilots now,and along with a couple more crew,was selected to deliver the new 737s to Dublin. he has done this now on quite a few times.


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How much does a Boeing 737 wing bend/deflect in cruise conditions?
As a part of my ongoing research of a structural joint analysis of a Boeing 737, I have been looking for sources where I may be able to find the bending/deflection data during cruise conditions. I have found sources that may not be considered reliable, however; would anyone be able to assist me with the above data from source that would be considered valid for justification.

If you can share the sources you have found so far it could help to confirm with any new sources that are found.

I doubt you will find this information, it's probably considered proprietary of Boeing and not released to the public because the data is likely not required for certification.

https://www.youtube.com/watch?v=dv4J1FgQtfM&index=10&list=LLCGHFD1ooc9TX7DUEh0AkPA


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How does the Bombardier CSeries compare to existing single-aisle jet-liners?
With news breaking in that Airbus will acquire a large part of Bombardier's CSeries program, I'm curious, just how much better are the new planes from Bombardier compared to single aisle planes like the 737 and 320 series?
Aircraft manufacturers drop superficial numbers in their press announcements like, "10% more fuel efficient", etc. It would be great to hear some more technical differences / flying characteristics etc.

Better is a very subjective term; what do you mean by it?

This site lists the CS300's consumption at 1950 kg/h. For the 737-600, the same list gives 2200 kg/h. Both planes seem to have similar MTOWs and service ranges. For the A319ceo, the same source gives also about 2200 kg/h. With a 15% fuel burn save over the ceo, I suppose the A319neo would burn about 1870 kg/hr (though the A319neo has larger MTOW and  range than the CS300). The A319neo seems to be difficult to sell.

@bjelleklang I guess that's what I'm trying to understand. The press reports it as "better". I'm trying to understand just how it is better. :-)

IMO, the biggest advantage of the CSeries over the 737 and 320 is its ability to operate out of airports with steep approaches, like London City Airport. http://economyclassandbeyond.boardingarea.com/2017/04/26/bombardier-obtains-cseries-cs100-certification-for-steep-approaches-featuring-lcy/


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How is a fly-by-wire system realized in big planes?
For example if whole system is build on CAN protocol that give maximum rate of 9000 messages per second with IMHO is quite low number for big plane.
Can you give me any example how this problem was solved?
Do they divide system into subsystem or use protocols like Ethernet IP?
Or maybe that number of messages is enough because they're sending only critical information?

9000 messages per second with IMHO is quite low number for big plane - why?  What reference do you have?  What number do you expect?

The problem with CAN for aviation purposes is that one bad device can disable the whole bus, because it relies on the common clock for arbitration. That's good enough for ground vehicles that can simply stop, but not for aircraft.

In fact, ARINC 429 is used in the "federated" avionics, this is the "old" system used in many aircraft like A320, B737, ...

Federated avionics require a lot of wires which generates a lot of weight. In ARINC we have approximately one wire per device, so the speed (100Kbps or 12,5Kbps depending on the selected mode) is sufficient.
ARINC 429 Architecture :

In "new" aircraft like A350 or B787 the industry use the Integrated Modular Avionics in order to reduce weight and reduce the number of S/N to stock.

In this kind on avionic all computers are merged in a couple of "cabinet" composed of multiple core processor units, shared ROM, shared RAM, shared graphic cards.
All these cards are linked, in the cabinet, with the Backplane BUS (ARINC 659), which operates at 60Mbps as a commercial aviation bus
All cabinet are linked ,each other and with actuators, using AFDX (ARINC 664) who look like Ethernet protocol and work at the speed of 100Mbit/s.
There is a lot of different IMA architecture with the same principle, but some differences. This is one on them, in this picture you can replace PCI Ex. by ARINC 659 :

Regarding CAN bus, Airbus use in in this A380 (http://www.aviationtoday.com/av/issue/feature/can-bus-in-aviation_31468.html)
Sources :
http://www.interfacebus.com/Design_Connector_Avionics.html
http://www.modern-avionics.com/
https://en.wikipedia.org/wiki/Avionics_Full-Duplex_Switched_Ethernet

Fly By Wire is not necessarily based on digital computation, as an example the CONCORDE had FBW with analog computation.
With modern aircrafts the iteration rate is increased by increasing the number of buses, thus in ARINC 429 systems every computer receives several buses and may use 2 or 3 output buses.
Most FBW as conventional control are hydraulically powered, the difference is in the control, instead of being fully mechanical, the stick is connected to electrical transducers that send an input to a computing system. The servo control instead of having a mechanical control, it has an electrical control, the main power remaining hydraulic.


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How would a helicopter deal with auto rotation when it transports a hanging payload?
How would a helicopter deal with auto rotation when it has a payload? Will it deploy it's payload and continue with auto rotation as normal? Can't find much online, this research is for my senior design.

Any help would be greatly appreciated. If you can give me something to read and learn further for myself, that would also be great.

According to the video's I've seen, an auto-rotation with a slung load is pretty much impossible at the altitudes/speeds they would be flying at.

Can you get a friendly Part 133 (or your country's equivalent) operator to provide their Rotorcraft Load Combination Flight Manual (RLCFM) or equivalent document? It should cover their procedure for auto during vertical reference (external load) flying...

Thank you all for your kind responses. We spoke to the sponsor of our project and arrived to the following conclusion: "A vehicle as this would require multiple engines".
Dropping the load would not be an option as our theortical mission would have us flying over densely populated areas. They also mentioned dropping a load of the size we are transporting would lead to wreck (because of center of gravity). @UnrecognizedFallingObject

@AlexisMoreno -- Autorotation procedures are still needed in multi-engine helicopters (due to say transmission trouble) although you are correct that external load missions over densely populated areas do require a multi-engine helicopter

@UnrecognizedFallingObject Yes you are correct. It would be neglectful to not mention a plan for when all the engines are inoperative. How would an aircraft land from an autorotation if it has an external load. I've started to read the Rotorcraft Load Combination Flight Manual.

In theory, with that load, the rotor revs will be higher during the descent, and releasing the load just before flaring will give the pilot more rotor energy to control the aircraft with the collective in the last stage of the landing.
But it would be more prudent, in my opinion, to release the load as soon as possible. After all, in any dead stick landing, the lighter the aircraft, the better...

Yeah, my first move would be to hit the "bye bye" knob on the hanging load.

Keep in mind that there are operations (power line maintenance, heli-rescue) where your hanging load is a human being.  Dumping them on the ground from altitude might not be so healthy for them!

@UnrecognizedFallingObject Autorotation usually isn't possible below 700 feet AGL, I'm not sure what power lines or rescue's are above 700 AGL. At the 100-150' AGL that most power line/rescue operations take place at, personally, I'd rather take my chance being dumped than having a helicopter land hard on top of me.

@UnrecognizedFallingObject  Do you actually transport people in a net using the cargo hook as an external load?

@KorvinStarmast -- look up Class B Human External Cargo if you want the technical term -- it'll be a harness system that attaches to a line of some flavor or another :) but the exact system is unimportant from the "what to do in an auto" standpoint

@UnrecognizedFallingObject There's a difference between using a cargo hook and a hoist. How about you answer my question.

@KorvinStarmast -- ah.  I don't know of any non-hoist Class B HEC ops, but I haven't seen anything that definitively rules them out either.

@UnrecognizedFallingObject The question seems be about cargo hook stuff, from what's been offered.  The losing an engine (or both) when someone's on the hoist is a different flavor of nightmare ...

Would you rather be dropped? or dragged into the ground doing 70 knots? nothing the pilot can do if its not capable of hovering after the loss of 1 engine. and yes, Class D some times is done with single engine's. search "North Shore Helicopter Rescue" Also auto's are possible from 500 feet, probably lower with a better pilot than I.

From the Operator's Manual of UH-1D/H, which are single engine helicopters:
9-13 Engine Failure - Low Altitude/Low Airspeed, and 9-15 Engine Failure - Cruise both describe the procedures for establishing autorotation. Both refer to jettisoning external loads, for instance 9-15:

When engine failure occurs during cruise flight, proceed as follows:

Collective pitch - Adjust as necessary. Establish auto rotational glide.
External stores - Jettison as appropriate
Land

For civil helicopters in the USA, external load operations are covered by 14 CFR part 133, which defines several classes of external loads and the operating rules for certification. In order to be certified the helicopter operator must provide a Rotorcraft-Load Combination Flight Manual (RLCFM).
An example of an RLCFM is found here, it does not contain any special procedures for autorotation upon engine failure. References to Long Line Operations in an R44 for agricultural activities are found here.
Autorotation upon engine failure and carrying an external load are high workload situations with a higher than normal inherent danger. Combining the two is not a good idea: FAA AC 133-1B specifies that the emergency release mechanism of the external load must be demonstrated before certification.

Generally last minute configuration changes have adverse outcomes as the aircraft configuration creates instability which impacts judgement and the ability to perform maneuvers, such as auto rotation.
With sling loads there are added complications which include:

ground crew likely in harms way
higher lift requirements (impacting rotor loading and stored energy requirements)
adverse handling due to the "flexible" coupling between the load and the aircraft
normally low altitudes for sling loads
many loads cannot be quickly shed

I have not been specifically trained for sling loads, but I believe that the decision will first be influenced by altitude, then payload weight, then type of payload and release mechanism (if any), etc.
For your project, you might try to get some Army training materials, and I would search the journals and magazines for articles.  The company "doctrine" will change depending upon the business, the region and the regulatory agencies involved.